Smoke test for a vacuum leak
 

Working on a P0171 and P0174 and vacuum leak issue. Using a Snap-on smoke tester. Lots of smoke coming from the back of the round black tube that feeds the injectors(?) on the last cylinder on the right side and the valve cover right at that cylinder. What is my next step? Thanks in advance. Tbrown

Re: Smoke test for a vacuum leak
 

Can you take a photo of what you're referencing?

Re: Smoke test for a vacuum leak
 

The location you describe is where the pcv system leaves the engine and is piped into the intake manifold...

A broken pipe or cracked manifold...(very common issue) will give you the lean codes you are seeing...

Pull the intake and heck it for cracks and broken hoses....renew every hose and use new sealing O rings....

:chevy::chevy::chevy:

Re: Smoke test for a vacuum leak
 

Thanks for the info. I will look closer tomorrow and see exactly where it's coming from. Probably have to use a mirror.

Re: Smoke test for a vacuum leak
 

Checked as best I could to see where the smoke is coming from and I am 99% sure it is only coming from the valve cover gasket. I think I will replace that and go from there. I'll keep you posted.

Re: Smoke test for a vacuum leak
 

The drivers side rocker cover has the pcv feed vent in the end closest to the transmission.

There is a new style cover available that corrects a lot of the fuming issues that occur with the early covers...

Take the cover off and replace the sealing rubber style gasket,,,,

Check the pcv feed hose is in place and is not cracked or split...if the hose is really hard it should be replaced...

:chevy::chevy::chevy:

Re: Smoke test for a vacuum leak
 

I took the right (passenger) cover off and the gasket was pushed out about 2 inches. The rear bolt was also bent. This is the side the donor vehicle was hit on so I figure that is what caused the problem. I straightened the bolt and will replace the gasket tomorrow. I would have never found the leak without the smoke machine. Not too hard of a fix if nothing else turns up.